Abstract Polyurethane (PU) elastomers with their broad range of strength and elasticity are ideal materials for additive manufacturing of shapes with gradients of mechanical properties. By adjusting the mixing ratio of different polyurethane reactants during 3D-printing it is possible to change the mechanical properties. However, to guarantee intra- and inter-layer adhesion, it is essential to know the reaction kinetics of the polyurethane reaction, and to be able to influence the reaction speed in a wide range. In this study, the effect of adding three different catalysts and two inhibitors to the reaction of polyurethane elastomers were studied by comparing the time of crossover points between storage and loss modulus G′ and G′′ from time sweep tests of small amplitude oscillatory shear at 30°C. The time of crossover points is reduced with the increasing amount of catalysts, but only the reaction time with one inhibitor is significantly delayed. The reaction time of 90% NCO group conversion calculated from the FTIR-spectrum also demonstrates the kinetics of samples with different catalysts. In addition, the relation between the conversion as determined from FTIR spectroscopy and the mechanical properties of the materials was established. Based on these results, it is possible to select optimized catalysts and inhibitors for polyurethane 3D-printing of materials with gradients of mechanical properties.

中文翻译：

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使用活性添加剂进行 3D 打印的聚氨酯弹性体的流变和机械梯度特性

摘要 聚氨酯 (PU) 弹性体具有广泛的强度和弹性，是增材制造具有梯度机械性能的形状的理想材料。通过在 3D 打印过程中调整不同聚氨酯反应物的混合比例，可以改变机械性能。然而，为了保证层内和层间的粘合，必须了解聚氨酯反应的反应动力学，并且能够在大范围内影响反应速度。本研究通过比较小振幅振荡剪切时间扫描试验中储能模量和损耗模量 G' 和 G'' 之间的交叉点时间，研究了加入三种不同催化剂和两种抑制剂对聚氨酯弹性体反应的影响。 30°C。随着催化剂用量的增加，交叉点的时间减少，但只有一种抑制剂的反应时间显着延迟。从 FTIR 光谱计算的 90% NCO 基团转化的反应时间也证明了具有不同催化剂的样品的动力学。此外，建立了由 FTIR 光谱测定的转化率与材料机械性能之间的关系。基于这些结果，可以选择优化的催化剂和抑制剂，用于具有梯度机械性能的材料的聚氨酯 3D 打印。从 FTIR 光谱计算的 90% NCO 基团转化的反应时间也证明了具有不同催化剂的样品的动力学。此外，建立了由 FTIR 光谱测定的转化率与材料机械性能之间的关系。基于这些结果，可以选择优化的催化剂和抑制剂，用于具有梯度机械性能的材料的聚氨酯 3D 打印。从 FTIR 光谱计算的 90% NCO 基团转化的反应时间也证明了具有不同催化剂的样品的动力学。此外，建立了由 FTIR 光谱测定的转化率与材料机械性能之间的关系。基于这些结果，可以选择优化的催化剂和抑制剂，用于具有梯度机械性能的材料的聚氨酯 3D 打印。